Black Velvet Alocasia

Plant of the Week

Black Velvet Alocasia Latin: Alocasia reginula

Black-leaved plants have always intrigued me, probably because of some deep-seated
emotional attachment to my first car, but that’s another story. One of the blackest
plants I know is a houseplant belonging to the philodendron family called Black Velvet
Alocasia (Alocasia reginula). The leaves look more like a lump of charcoal than a plant.

Black Velvet alocasia is one of several species of alocasias native in Southeast Asia,
with this plant probably coming from the jungles of Borneo. It and its kin were collected
during the 1860s by English plant collectors who scoured the jungles of the world
looking for new orchids and houseplants.

Unlike most alocasia, Black Velvet forms a branched, rhizomatous stem that can produce
plants up to 18 inches wide. It’s usually less than a foot high. The thick, but brittle
leaves are heart-shaped ovals about the size of a saucer. The leaf blade is a velvety
black offset by platinum colored veins. The undersurface of the leaf is purplish.

To understand how a plant can be black, first me need to consider what makes the typical
plant green. The run of the mill plant is green because the middle portion of the
visible light spectrum - the green and yellow portion - is not used by the plant but
instead reflected back to our eye. Chlorophyll uses the red and blue end of the visible
spectrum in photosynthesis and casts off that portion of the spectrum not needed.

Physicists like to talk about black holes in space, concentrations of matter so dense
that not even electromagnetic waves escape their tremendous gravitational pull. Black-leafed
plants are living black holes in that they absorb light energy across the visible
spectra, allowing none to be reflected back. Alternatively, the white veins of Black
Velvet alocasia reflect almost all of the visible spectra producing the black on white
contrast of the plant.

This physical reality is easy to illustrate. Compare the temperature inside a black
car and a white car in the Arkansas summertime. The somewhat cooler white car is cooler
because more of the spectrum is being reflected back while the black car absorbs the
energy and converts it to heat.

But this velvety blackness is just an illusion, for if you crush the leaf, the familiar
green of chlorophyll issues forth. In their low-light environment black-leaved plants
must have made the evolutionary assumption that all light energy is good, thus hoarding
light rays like McScrooge hoarded his wealth in the cartoon classics of my youth.

Black Velvet alocasia has moved from the obscurity of the plant collector to mainstream
status because of the alchemy of the plant tissue culture specialists. Tissue culture
labs have learned how to propagate this species en mass, thus making liners available to greenhouse growers across the nation. Plants are
now showing up in better nurseries plus some of the mass market outlets.

In the home, Black Velvet alocasia should be given bright conditions but not direct
sun. A north or east-facing window is ideal but any location suitable for an African
violet should work. The plant is somewhat slow growing, so acquire as large a plant
as possible.

Transplant the plant about once a year, but keep the pot size as small as possible.
It’s not a heavy feeder so avoid the temptation of trying to force it to grow fast
by extra fertilization. Like most members of the philodendron family, never let the
plant sit in standing water.

The University of Arkansas Division of Agriculture does not maintain lists of retail
outlets where these plants can be purchased. Please check your local nursery or other
retail outlets to ask about the availability of these plants for your growing area.